Haeco-csg
Encyclopedia
The Haeco-CSG or Holzer Audio Engineering-Compatible Stereo Generator system is an analog electronic device and method developed by Howard Holzer, Chief Engineer at A&M Records
in Hollywood, California
. His company, Holzer Audio Engineering, developed the system in the 1960s during the years of transition from monaural
to stereophonic
popular music recording. The process was used primarily from about 1968 until 1970 but still exists on a significant number of recordings made during the time.
LP
records
that when played on monaural equipment would allow the 2 channel stereo mix to automatically "fold-down" properly to a single monaural channel.
The reason for the process is the compatibility issue between stereophonic and monaural recordings: information which is identical on both the left and right channels of a stereophonic mix sounds too loud when played back on monaural AM
and FM radio
stations and phonograph
s. When the left and right channels are summed together, any musical parts that are common to both channels combine to be 6 decibel
s louder than they are in the same mix when played in stereo. Vocals, solo instruments and bass lines are often mixed equally to both stereo channels — these sounds tend be too loud when heard in mono.
Due to technical issues in the record playback process the practice of creating separate mono and stereo mixes of the same recording was common during the 1960s. This also required manufacturing and distributing mono and stereo versions of the same album title. The Haeco-CSG system appeared to be an attractive option for record companies and retailers by allowing them to cut costs. The engineers would only have to produce a single mix, the record companies would only have to manufacture and distribute one version, and vendors wouldn't have to waste space stocking two different products.
The system electrically rotated the waveform of the right channel by up to 120 degrees to control the build up of center information during a simple mono downmix. It's not known how exactly the circuit accomplished this; it did however do this without slightly delaying one channel. The most common listing of 90 degrees out of phase corresponds to Haeco's own recommended setting of the +3dB build up, where as no build-up would require a 120 degree offset. This setting was most commonly used because of its robustness against polarity reversal of audio interconnects down the chain, which can affect the resulting audio when downmixed to mono. Information that is not common to both channels is entirely unaffected as there is no offset phase wave to cancel with.
Due to complicated issues of phase
and frequency
it is difficult to predict exactly how the reduction from two channels to one will affect the sound of a particular instrument. Therefore mono sound from a true mono mix is always preferable to the use of an automatic process such as Haeco-CSG which converts stereo to mono.
took out a full page advertisement in the April 6, 1968 issue of Billboard Magazine
to promote its adoption of the technique, calling it "CSG Stereo." Many A&M Records LP releases during the period including popular titles by Sérgio Mendes
and Herb Alpert
were released with this audio process starting in September 1968. Other record labels soon followed suit, and an estimated 10% of all stereophonic albums released during the late 1960s and early 1970s employed the system. Other labels known to have used the system include Warner Bros. Records
and Reprise Records
.
One of the biggest selling albums using the process is The Association's Greatest Hits
, released in 1968. Most of the studio recordings on Wheels of Fire
by Cream
also used this process. Early copies from 1968 of Neil Young's self titled debut album
used the system.
broadcasting was not introduced until 1982 and did not become popular until the mid 1980s.
Many promotional singles and some commercial singles from the Warner/Reprise/Atlantic label group from this era had "CSG Mono Process" or "CSG Process" printed on the labels. Artists included Frank Sinatra
, Gordon Lightfoot
, James Taylor
, Seals and Crofts
. Warner subsidiary labels such as Atlantic issued a series of mono radio station promotional LPs by Progressive Rock
artists circa 1968-1970 which are now rare collectibles. The series included titles by Led Zeppelin
, Yes
and many others. In 1979 the Warner distributed label Sire Records
issued a promotional single of "Pop Muzik
" by M
which contains both short and long versions in CSG processed stereo. This may be the latest known recording to utilize the CSG stereo process.
stage, near the end of the production chain for LP records. In such cases, the earliest analog master tapes for these recordings still exist without Haeco-CSG processing. Therefore, when these recordings employing the Haeco-CSG process are properly remastered for Compact Disc the effects of the process can and should be removed. Remastering without the effect usually requires the work of a well informed audio engineer
who takes the extra time necessary to locate the correct master tape copies. Steve Hoffman is a notable example of one who has made this a priority.
However the Haeco-CSG processing was often applied at the master tape mix session. This, in effect, makes it a permanent part of the stereo recording. However, the process can still be reversed through modern digital reprocessing. Unfortunately, many Compact Disc
s of these processed albums still are encoded with the system, causing the center channel blurring effect even on modern digital playback systems.
software by digitally re-rotating phase of the right channel back by the correct number of degrees.
Adobe Audition
is able to remove the effect using the Graphic Panner tool (the Automatic Phase Correction tool is unable to accurately do this) by manually selecting the "Phase -90 degrees" preset. The "Auto Center Phase" and "Learn Phase" features will also work, but are not recommended. There are sometimes slight offsets caused by various mixing effects and, to a lesser extent, tape-head misalignment; studio reverb or naturally decaying reverb is a prime example. As a waveform decays in a large room, it naturally changes phase. In Auto Center phase, this is (generally) shown as the upper frequencies making a drastic change. Tape head misalignment (azimuth) also will cause a phase change in upper frequencies. One should be aware of this when attempting to remove Haeco processing and not use auto-phase options. Azimuth alignment adjustment tools can however be used AFTER Haeco has been removed.
The "Stereo Tool" plug-in used in conjunction with Winamp
is also able to (mostly) reverse the effects of Haeco-CSG. To do this enable "Stereo Image Processing" option and adjust the "Angle" setting right to 90 degrees. By adjusting the Winamp plug-in settings under the "Preferences" tab to "out_disk" it is also possible to capture the reprocessed digital audio to a wave or mp3 file.
One can also use a simple channel mixer found in most workstations to do a simple correction. By having each channel contain 75% of itself and 25% of the other channel channel, the "blended" result will be mostly in phase. This, however, can cause the stereo separation to be diminished by a slight degree.
A&M Records
A&M Records is an American record label owned by Universal Music Group that operates under the mantle of its Interscope-Geffen-A&M division.-Beginnings:...
in Hollywood, California
Hollywood, Los Angeles, California
Hollywood is a famous district in Los Angeles, California, United States situated west-northwest of downtown Los Angeles. Due to its fame and cultural identity as the historical center of movie studios and movie stars, the word Hollywood is often used as a metonym of American cinema...
. His company, Holzer Audio Engineering, developed the system in the 1960s during the years of transition from monaural
Monaural
Monaural or monophonic sound reproduction is single-channel. Typically there is only one microphone, one loudspeaker, or channels are fed from a common signal path...
to stereophonic
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
popular music recording. The process was used primarily from about 1968 until 1970 but still exists on a significant number of recordings made during the time.
Reasons for Using the System
The idea behind Haeco-CSG was to create stereophonic vinylVinyl
A vinyl compound is any organic compound that contains a vinyl group ,which are derivatives of ethene, CH2=CH2, with one hydrogen atom replaced with some other group...
LP
LP album
The LP, or long-playing microgroove record, is a format for phonograph records, an analog sound storage medium. Introduced by Columbia Records in 1948, it was soon adopted as a new standard by the entire record industry...
records
Gramophone record
A gramophone record, commonly known as a phonograph record , vinyl record , or colloquially, a record, is an analog sound storage medium consisting of a flat disc with an inscribed, modulated spiral groove...
that when played on monaural equipment would allow the 2 channel stereo mix to automatically "fold-down" properly to a single monaural channel.
The reason for the process is the compatibility issue between stereophonic and monaural recordings: information which is identical on both the left and right channels of a stereophonic mix sounds too loud when played back on monaural AM
AM broadcasting
AM broadcasting is the process of radio broadcasting using amplitude modulation. AM was the first method of impressing sound on a radio signal and is still widely used today. Commercial and public AM broadcasting is carried out in the medium wave band world wide, and on long wave and short wave...
and FM radio
FM broadcasting
FM broadcasting is a broadcasting technology pioneered by Edwin Howard Armstrong which uses frequency modulation to provide high-fidelity sound over broadcast radio. The term "FM band" describes the "frequency band in which FM is used for broadcasting"...
stations and phonograph
Phonograph
The phonograph record player, or gramophone is a device introduced in 1877 that has had continued common use for reproducing sound recordings, although when first developed, the phonograph was used to both record and reproduce sounds...
s. When the left and right channels are summed together, any musical parts that are common to both channels combine to be 6 decibel
Decibel
The decibel is a logarithmic unit that indicates the ratio of a physical quantity relative to a specified or implied reference level. A ratio in decibels is ten times the logarithm to base 10 of the ratio of two power quantities...
s louder than they are in the same mix when played in stereo. Vocals, solo instruments and bass lines are often mixed equally to both stereo channels — these sounds tend be too loud when heard in mono.
Due to technical issues in the record playback process the practice of creating separate mono and stereo mixes of the same recording was common during the 1960s. This also required manufacturing and distributing mono and stereo versions of the same album title. The Haeco-CSG system appeared to be an attractive option for record companies and retailers by allowing them to cut costs. The engineers would only have to produce a single mix, the record companies would only have to manufacture and distribute one version, and vendors wouldn't have to waste space stocking two different products.
How the Technology Works
Haeco-CSG technology works on the basis of phase cancellation. When two waves that are not in phase are mixed, the resulting waveform has an attenuation in accordance to the degree of shift. For example, two waves which are 180 degrees out of phase will entirely cancel out when mixed together where as two waves which are entirely in phase will double in amplitude. A difference in phase between 180 and 0 degrees results in a partial cancellation, which is the effect Haeco-CSG takes advantage of.The system electrically rotated the waveform of the right channel by up to 120 degrees to control the build up of center information during a simple mono downmix. It's not known how exactly the circuit accomplished this; it did however do this without slightly delaying one channel. The most common listing of 90 degrees out of phase corresponds to Haeco's own recommended setting of the +3dB build up, where as no build-up would require a 120 degree offset. This setting was most commonly used because of its robustness against polarity reversal of audio interconnects down the chain, which can affect the resulting audio when downmixed to mono. Information that is not common to both channels is entirely unaffected as there is no offset phase wave to cancel with.
Negative Effects
Generally speaking Haeco-CSG has a degrading effect on the performance of both stereo and mono sounds processed through the system. The effect can vary substantially from one recording to another depending on the characteristics of the original unprocessed sound. The system "blurs" the focus of lead vocals and other sounds mixed to the center of a stereo recording. As bass frequencies are centered on most recordings it also causes a partial loss of low frequency information, making the resulting sound somewhat "tinny." This negative effect can be heard on any stereo speaker system, but makes headphone listening particularly un-natural sounding. This is because the lead vocalist or performer's audio waveform would be attempting to partially cancel itself inside the listener's head, confusing the brain's audio positioning sense.Due to complicated issues of phase
Phase (waves)
Phase in waves is the fraction of a wave cycle which has elapsed relative to an arbitrary point.-Formula:The phase of an oscillation or wave refers to a sinusoidal function such as the following:...
and frequency
Audio frequency
An audio frequency or audible frequency is characterized as a periodic vibration whose frequency is audible to the average human...
it is difficult to predict exactly how the reduction from two channels to one will affect the sound of a particular instrument. Therefore mono sound from a true mono mix is always preferable to the use of an automatic process such as Haeco-CSG which converts stereo to mono.
Recordings Known
Atlantic RecordsAtlantic Records
Atlantic Records is an American record label best known for its many recordings of rhythm and blues, rock and roll, and jazz...
took out a full page advertisement in the April 6, 1968 issue of Billboard Magazine
Billboard (magazine)
Billboard is a weekly American magazine devoted to the music industry, and is one of the oldest trade magazines in the world. It maintains several internationally recognized music charts that track the most popular songs and albums in various categories on a weekly basis...
to promote its adoption of the technique, calling it "CSG Stereo." Many A&M Records LP releases during the period including popular titles by Sérgio Mendes
Sergio Mendes
Sérgio Santos Mendes is a Brazilian musician. He has released over thirty-five albums, and plays bossa nova heavily crossed with jazz and funk....
and Herb Alpert
Herb Alpert
Herbert "Herb" Alpert is an American musician most associated with the group variously known as Herb Alpert & the Tijuana Brass, Herb Alpert's Tijuana Brass, or TJB. He is also a recording industry executive — he is the "A" of A&M Records...
were released with this audio process starting in September 1968. Other record labels soon followed suit, and an estimated 10% of all stereophonic albums released during the late 1960s and early 1970s employed the system. Other labels known to have used the system include Warner Bros. Records
Warner Bros. Records
Warner Bros. Records Inc. is an American record label. It was the foundation label of the present-day Warner Music Group, and now operates as a wholly owned subsidiary of that corporation. It maintains a close relationship with its former parent, Warner Bros. Pictures, although the two companies...
and Reprise Records
Reprise Records
Reprise Records is an American record label, founded in 1960 by Frank Sinatra. It is owned by Warner Music Group, and operated through Warner Bros. Records.-Beginnings:...
.
One of the biggest selling albums using the process is The Association's Greatest Hits
Greatest Hits (The Association album)
Greatest Hits is the first compilation album by The Association, released in 1968 by Warner Bros. Records. The album peaked at #4 on the Billboard 200 album chart. It has sold more than 2 million copies in the U.S. alone, making it the group's biggest seller.The collection combines hit singles...
, released in 1968. Most of the studio recordings on Wheels of Fire
Wheels of Fire
Wheels of Fire is the name of a double album recorded by Cream. The release was largely successful, scoring the band a #3 peak in the United Kingdom and a #1 in the United States, and became the world's first platinum-selling double album....
by Cream
Cream (band)
Cream were a 1960s British rock supergroup consisting of bassist/vocalist Jack Bruce, guitarist/vocalist Eric Clapton, and drummer Ginger Baker...
also used this process. Early copies from 1968 of Neil Young's self titled debut album
Neil Young (album)
Neil Young is the self-titled debut studio album by Canadian musician Neil Young, which was his debut release as a solo artist following his departure from the band Buffalo Springfield...
used the system.
Use of Haeco-CSG in Promotional Recordings for Radio
The original intention of using Haeco-CSG on commercial LP releases was rather short lived, however, use of the process continued well into the mid 1970s on promotional records sent to radio stations. Many commercial FM Rock stations did not transition from mono to stereo broadcasting until the mid to late 1970s. AM Pop music stations continued to broadcast in mono, as AM stereoAM stereo
AM stereo is a term given to a series of mutually incompatible techniques for wireless radio broadcasting stereo audio in the AM band in a manner that is compatible with standard AM receivers...
broadcasting was not introduced until 1982 and did not become popular until the mid 1980s.
Many promotional singles and some commercial singles from the Warner/Reprise/Atlantic label group from this era had "CSG Mono Process" or "CSG Process" printed on the labels. Artists included Frank Sinatra
Frank Sinatra
Francis Albert "Frank" Sinatra was an American singer and actor.Beginning his musical career in the swing era with Harry James and Tommy Dorsey, Sinatra became an unprecedentedly successful solo artist in the early to mid-1940s, after being signed to Columbia Records in 1943. Being the idol of the...
, Gordon Lightfoot
Gordon Lightfoot
Gordon Meredith Lightfoot, Jr. is a Canadian singer-songwriter who achieved international success in folk, folk-rock, and country music, and has been credited for helping define the folk-pop sound of the 1960s and 1970s...
, James Taylor
James Taylor
James Vernon Taylor is an American singer-songwriter and guitarist. A five-time Grammy Award winner, Taylor was inducted into the Rock & Roll Hall of Fame in 2000....
, Seals and Crofts
Seals and Crofts
Seals and Crofts is a band made up of Jim Seals and Dash Crofts . The soft rock duo was one of the most successful musical acts of the 1970s. They are best known for their hits "Summer Breeze" and "Diamond Girl"...
. Warner subsidiary labels such as Atlantic issued a series of mono radio station promotional LPs by Progressive Rock
Progressive rock
Progressive rock is a subgenre of rock music that developed in the late 1960s and early 1970s as part of a "mostly British attempt to elevate rock music to new levels of artistic credibility." John Covach, in Contemporary Music Review, says that many thought it would not just "succeed the pop of...
artists circa 1968-1970 which are now rare collectibles. The series included titles by Led Zeppelin
Led Zeppelin
Led Zeppelin were an English rock band, active in the late 1960s and throughout the 1970s. Formed in 1968, they consisted of guitarist Jimmy Page, singer Robert Plant, bassist/keyboardist John Paul Jones, and drummer John Bonham...
, Yes
Yes (band)
Yes are an English rock band who achieved worldwide success with their progressive, art, and symphonic style of rock music. Regarded as one of the pioneers of the progressive genre, Yes are known for their lengthy songs, mystical lyrics, elaborate album art, and live stage sets...
and many others. In 1979 the Warner distributed label Sire Records
Sire Records
Sire Records is an American record label, owned by Warner Music Group and distributed through Warner Bros. Records.-Beginnings:The label was founded in 1966 as Sire Productions by Seymour Stein and Richard Gottehrer, each investing ten thousand dollars into the new company. Its early releases as a...
issued a promotional single of "Pop Muzik
Pop Muzik
"Pop Muzik" is a 1979 hit song by M, a project by Robin Scott.-Concept and chart performance:Robin Scott describes the genesis of "Pop Muzik" this way:...
" by M
M (band)
M was English musician Robin Scott's brief but very successful new wave/synthpop project in the late 1970s and early 1980s. M is most known for the 1979 hit "Pop Muzik", which reached #2 in the UK Singles Chart in May 1979, and #1 in the U.S. Billboard Hot 100 chart on 3 November 1979...
which contains both short and long versions in CSG processed stereo. This may be the latest known recording to utilize the CSG stereo process.
Modern Remastering Without Haeco-CSG
Haeco-CSG can be applied during the masteringAudio mastering
Mastering, a form of audio post-production, is the process of preparing and transferring recorded audio from a source containing the final mix to a data storage device ; the source from which all copies will be produced...
stage, near the end of the production chain for LP records. In such cases, the earliest analog master tapes for these recordings still exist without Haeco-CSG processing. Therefore, when these recordings employing the Haeco-CSG process are properly remastered for Compact Disc the effects of the process can and should be removed. Remastering without the effect usually requires the work of a well informed audio engineer
Audio engineering
An audio engineer, also called audio technician, audio technologist or sound technician, is a specialist in a skilled trade that deals with the use of machinery and equipment for the recording, mixing and reproduction of sounds. The field draws on many artistic and vocational areas, including...
who takes the extra time necessary to locate the correct master tape copies. Steve Hoffman is a notable example of one who has made this a priority.
However the Haeco-CSG processing was often applied at the master tape mix session. This, in effect, makes it a permanent part of the stereo recording. However, the process can still be reversed through modern digital reprocessing. Unfortunately, many Compact Disc
Compact Disc
The Compact Disc is an optical disc used to store digital data. It was originally developed to store and playback sound recordings exclusively, but later expanded to encompass data storage , write-once audio and data storage , rewritable media , Video Compact Discs , Super Video Compact Discs ,...
s of these processed albums still are encoded with the system, causing the center channel blurring effect even on modern digital playback systems.
Digital Reprocessing
Haeco-CSG processing can be reversed through digital audio workstationDigital audio workstation
A digital audio workstation is an electronic system designed solely or primarily for recording, editing and playing back digital audio. DAWs were originally tape-less, microprocessor-based systems such as the Synclavier and Fairlight CMI...
software by digitally re-rotating phase of the right channel back by the correct number of degrees.
Adobe Audition
Adobe Audition
Adobe Audition is a digital audio workstation from Adobe Systems featuring both a multitrack, non-destructive mix/edit environment and a destructive-approach waveform editing view.-Origins:...
is able to remove the effect using the Graphic Panner tool (the Automatic Phase Correction tool is unable to accurately do this) by manually selecting the "Phase -90 degrees" preset. The "Auto Center Phase" and "Learn Phase" features will also work, but are not recommended. There are sometimes slight offsets caused by various mixing effects and, to a lesser extent, tape-head misalignment; studio reverb or naturally decaying reverb is a prime example. As a waveform decays in a large room, it naturally changes phase. In Auto Center phase, this is (generally) shown as the upper frequencies making a drastic change. Tape head misalignment (azimuth) also will cause a phase change in upper frequencies. One should be aware of this when attempting to remove Haeco processing and not use auto-phase options. Azimuth alignment adjustment tools can however be used AFTER Haeco has been removed.
The "Stereo Tool" plug-in used in conjunction with Winamp
Winamp
Winamp is a media player for Windows-based PCs and Android devices, written by Nullsoft, now a subsidiary of AOL. It is proprietary freeware/shareware, multi-format, extensible with plug-ins and skins, and is noted for its graphical sound visualization, playlist, and media library features.Winamp...
is also able to (mostly) reverse the effects of Haeco-CSG. To do this enable "Stereo Image Processing" option and adjust the "Angle" setting right to 90 degrees. By adjusting the Winamp plug-in settings under the "Preferences" tab to "out_disk" it is also possible to capture the reprocessed digital audio to a wave or mp3 file.
One can also use a simple channel mixer found in most workstations to do a simple correction. By having each channel contain 75% of itself and 25% of the other channel channel, the "blended" result will be mostly in phase. This, however, can cause the stereo separation to be diminished by a slight degree.